ECU Pinouts

The ECU is the very heart of your engine management system. Almost everything under the bonnet, and a lot of the stuff inside the car, connects to it in some way.

When things start going wrong, it's essential to check that signals are getting to or coming from the ECU, and that means testing the wiring. To help you identify what goes where, here are the pinouts for each generation of E30 ECU.

Jetronic

Pin	Function	Pin	Function	Image
1		14

Motronic 1.0

The Motronic 1.0 ECU employs a 35-pin plug to connect to all the engine bay components.

Pin	Function	Pin	Function	Image
1	Ignition coil output	19	Ground
2	Idle switch	20	Main relay
3	WOT switch	21	Tachometer
4	Cranking signal	22	AFM Temp sensor
5	Ground/Crank PosS Gnd	23	Inlet Air Temp/Crank SpS Gnd
6	AFM ground	24	O2 sensor signal *
7	AFM signal	25	Crank position sensor 1
8	Crank speed sensor 1	26	Crank position sensor 2
9	AFM supply	27	Crank speed sensor 2
10	Auto only special	28	Water Pressure switch
11	Fuel consumption gauge	29	A/C switch (if installed)
12		30	+Inlet Air Temp
13	Water Temp	31
14	Injector output cyl 3&4	32
15	Injector output cyl 1&2	33	ICV pulse
16	Ground	34	ICV pulse
17	Ground	35	Injector ground
18

Motronic 1.1/1.3

Pin	Function	Pin	Function	Pin	Function	Image
1		20		38
2